docs: def pluralize(singular):
      """Convert singular word to its plural form.
  
      Args:
          singular: A word in its singular form.
  
      Returns:
          The word in its plural form.
      """
      if singular in UNCOUNTABLES:
          return singular
      for i in IRREGULAR:
          if i[0] == singular:
              return i[1]
      for i in PLURALIZE_PATTERNS:
          if re.search(i[0], singular):
              return re.sub(i[0], i[1], singular)